I think your reasoning is sound. As someone in the midst of puppy training- get one BEFORE you have baby to take care of. And hopefully Daisy can help train the new pup.
I also think have a second lab can be very therapeutic when the inevitable happens. After we lost Kimber, we were heartbroken. We were so fortunate that our new neighbors just happened to get a lab puppy around the time we moved in. Magnus was such good puppy therapy for us as we grieved.